Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 1: Evolutionary and Population Dynamics

BP 1.3: Talk

Monday, March 26, 2007, 10:45–11:00, H43

A stochastic approach to group selection — •Arne Traulsen — Program for Evolutionary Dynamics, Harvard University, USA

A minimalist stochastic model of multi-level or group selection is discussed. A population is sub-divided into groups. Individuals reproduce; offspring are added to the same group. If a group reaches a certain size, it can split into two. Faster reproducing individuals lead to larger groups which split more often. It can be shown that this population structure acts as a suppressor of selection [1]. In this model, higher level selection emerges as a by-product of individual reproduction and population structure, allowing the evolution of cooperation. In a situation in which individuals interact with other members of the group in an evolutionary game which determines their fitness, one can derive a condition for the evolution of cooperation by group selection: if b/c> 1+ n/m then group selection favors cooperation [2]. The parameters B and c denote the benefit and cost of the altruistic act, while n and m denote the maximum group size and the number of groups. The model can be extended to more than two levels of selection and to include migration.

[1] A. Traulsen, A.M. Sengupta, and M.A. Nowak, J.Theor.Biol. 235, 393 (2005).

[2] A. Traulsen and M.A. Nowak, PNAS 103, 10952 (2006).